Lord English and the cali's will be fine without Gamzee, they'll grow up somewhere else without outside influence. This is probably the future Callie spoke of earlier where they grow up without talking to the Alpha Kids, Calliope takes over the body, and goes God Tier.

Nope!  Retcon Jane knows who Calliope is therefore Calliope still talked to the Alpha kids and in order to do so would require the technology that Gamzee provided for them.